A relatively new adolescent drug abuse instrument, the Personal Experience Inventory (PEI), was evaluated for convergent and predictive validity in a clinical sample of 140 youths being evaluated for drug treatment referral. The tool’s problem severity scales were compared to concurrent client (n = 140) and parent (n = 102) measures of drug abuse and related psychosocial functioning at intake and one-year later, to counselor intake ratings of problems and treatment need, to client treatment tenure, and to outcome functioning. PEI convergent validity coefficients (r) based on client concurrent measures at both data points and based on counselor ratings of drug abuse problem severity generally exceeded.50, whereas coefficients typically fell below.50 when the PEI was compared to the less direct client measures of psychosocial functioning and the parent measures. The predictive validity results indicate a moderately positive association between PEI scores and treatment and aftercare attendance and client functioning one-year later, particularly for the no-treatment subjects. The data are discussed within the context of growing evidence documenting psychometric adequacy for the PEI and the validity of self-report by adolescents in clinical settings.